Phosphorus Pollution in Lakes

We need to speed up recovery treatments of lakes or accept poor freshwater quality. 

In a new series of studies, leading scientists assess how to control phosphorus pollution in lakes. "In 40 % of Europe's lakes the water quality does not meet the demands of EUs Water Framework Directive, mainly due to phosphorus pollution. That is a huge problem for biodiversity and society and we need to put an effort into developing effective approaches to restore these lakes," says Associate Professor Kasper Reitzel, Department of Biology, University of Southern Denmark.

The special issue of Water Research brings together 60 authors from 12 countries. In a press release the journal writes: "Phosphorus is the biggest cause of water quality degradation worldwide, causing "dead zones," toxic algal blooms, loss of biodiversity and increased health risks for the plants, animals and humans that come in contact with polluted waters.

After decades with run-off from agriculture, human sewage and industrial practices, phosphorus has been stock piled at an alarming rate in our lake bed sediments. The scale of the problem is daunting, and even though enormous attempts are done to reduce the runoff humans are still pumping about 10 million tonnes of extra phosphorus into our freshwaters every year.

Long-term monitoring activities following the fate of phosphorus in lakes show that plants and animals don't recover for many years even if the phosphorus load is decreased. This is because phosphorus stored in bed sediments is released back to the water column and recycled in the lake."

So-called geoengineering in lakes is widely used to clean lakes from phosphorus pollution. Often used geoengineering methods are adding aluminum salts or modifying clays into the lake to lock excess phosphorus stored in the sediments. "However, results have not always been good. Often lake managers have used geoengineering uncritically in lakes where the external loading of phosphorus was not reduced enough or they have applied too low dosage because of the economy," says Sara Egemose, Department of Biology, University of Southern Denmark.

Source: Science Daily

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• Ecology
• Pollution
• Lake Management